1. Field of the Invention
This invention in general relates to a supply of power to electronic system components and in particular to a comparison of the desired voltage levels of that supply.
2. Description of the Related Art
Computer systems are information handling electronic systems which can be designed to give independent computing power to one user or a plurality of users. Computer systems may be found in many forms including, for example, mainframes, minicomputers, workstations, servers, personal computers, internet terminals, notebooks, and embedded systems. Personal computer (PC) systems, such as the International Business Machines (IBM) (tm) compatible PC systems, include desk top, floor standing, or portable versions. A typical PC system includes a processor, associated memory and control logic, and a number of peripheral devices that provide input and output for the system. Such peripheral devices often include display monitors, keyboards, mouse-type input devices, floppy and hard disk drives, CD-ROM drives, printers, network capability cards, terminal devices, modems, televisions, sound devices, voice recognition devices, electronic pen devices, and mass storage devices such as tape drives, CD-R drives, or DVDs. Other types of computer systems may also include similar devices as well.
Computer systems and other types of electronic systems employ power supplies to provide power for a system within required parameters. Some types of power supplies convert alternating current (AC) power to direct current (DC) power at regulated voltage levels required by the system for proper operation. Such voltage levels may include +/-12 VDC, +/-5 VDC, and +/-3.3 VDC. Some power supplies convert DC power having a first set of parameters to DC power having a second set of parameters. Some power supplies utilize batteries as the original power source.
Computer system components such as processors, memory devices, and other electronic circuits require power at specific voltage levels or ranges in order to operate properly. To ensure that the proper voltage level is provided, some components of a system may provide a voltage level indication signal to the power supply to indicate a desired voltage level for the supply of power to the component and, in some cases, other components of the system. An example of one such system is found in the patent application entitled "Voltage Supply Regulation Using Master/Slave Timer Circuit Modulation," inventor Alan E. Brown, Ser. No. 08/991,087, filed on Dec. 15, 1997, and having a common assignee, all of which is hereby incorporated by reference in its entirety.
For some electronic systems, it is economically desirable to limit the number of power supplies in the system. Accordingly, power for multiple components may be supplied from a single power supply. With such systems, proper design and manufacture techniques can usually ensure that all components of the system require the same voltage levels of power. However, the practical realities of today's computer industry are of low cost part assembly stores and frequent component upgrades. With such realities, compatibility of voltage requirements are not always assured. Such voltage level requirement miss-matches can lead to component substandard performance or component failure. An example of a system where a problem may occur is with multiprocessor computers where the different processors may have different desired voltage levels for the supply of power to each processor.
What is needed is a circuit to compare the desired voltage levels of different components and to provide indications of those comparisons in order to prevent damage to components in the event of non equivalent desired voltage levels.